From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752489AbeFDKBD (ORCPT ); Mon, 4 Jun 2018 06:01:03 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40566 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752387AbeFDKBA (ORCPT ); Mon, 4 Jun 2018 06:01:00 -0400 From: Srikar Dronamraju To: Ingo Molnar , Peter Zijlstra Cc: LKML , Mel Gorman , Rik van Riel , Srikar Dronamraju , Thomas Gleixner Subject: [PATCH 03/19] sched/numa: Simplify load_too_imbalanced Date: Mon, 4 Jun 2018 15:30:12 +0530 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1528106428-19992-1-git-send-email-srikar@linux.vnet.ibm.com> References: <1528106428-19992-1-git-send-email-srikar@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18060410-0016-0000-0000-000001D7738B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18060410-0017-0000-0000-0000322A0342 Message-Id: <1528106428-19992-4-git-send-email-srikar@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-04_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1805220000 definitions=main-1806040123 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently load_too_imbalance() cares about the slope of imbalance. It doesn't care of the direction of the imbalance. However this may not work if nodes that are being compared have dissimilar capacities. Few nodes might have more cores than other nodes in the system. Also unlike traditional load balance at a NUMA sched domain, multiple requests to migrate from the same source node to same destination node may run in parallel. This can cause huge load imbalance. This is specially true on a larger machines with either large cores per node or more number of nodes in the system. Hence allow move/swap only if the imbalance is going to reduce. Testcase Time: Min Max Avg StdDev numa01.sh Real: 516.14 892.41 739.84 151.32 numa01.sh Sys: 153.16 192.99 177.70 14.58 numa01.sh User: 39821.04 69528.92 57193.87 10989.48 numa02.sh Real: 60.91 62.35 61.58 0.63 numa02.sh Sys: 16.47 26.16 21.20 3.85 numa02.sh User: 5227.58 5309.61 5265.17 31.04 numa03.sh Real: 739.07 917.73 795.75 64.45 numa03.sh Sys: 94.46 136.08 109.48 14.58 numa03.sh User: 57478.56 72014.09 61764.48 5343.69 numa04.sh Real: 442.61 715.43 530.31 96.12 numa04.sh Sys: 224.90 348.63 285.61 48.83 numa04.sh User: 35836.84 47522.47 40235.41 3985.26 numa05.sh Real: 386.13 489.17 434.94 43.59 numa05.sh Sys: 144.29 438.56 278.80 105.78 numa05.sh User: 33255.86 36890.82 34879.31 1641.98 Testcase Time: Min Max Avg StdDev %Change numa01.sh Real: 435.78 653.81 534.58 83.20 38.39% numa01.sh Sys: 121.93 187.18 145.90 23.47 21.79% numa01.sh User: 37082.81 51402.80 43647.60 5409.75 31.03% numa02.sh Real: 60.64 61.63 61.19 0.40 0.637% numa02.sh Sys: 14.72 25.68 19.06 4.03 11.22% numa02.sh User: 5210.95 5266.69 5233.30 20.82 0.608% numa03.sh Real: 746.51 808.24 780.36 23.88 1.972% numa03.sh Sys: 97.26 108.48 105.07 4.28 4.197% numa03.sh User: 58956.30 61397.05 60162.95 1050.82 2.661% numa04.sh Real: 465.97 519.27 484.81 19.62 9.385% numa04.sh Sys: 304.43 359.08 334.68 20.64 -14.6% numa04.sh User: 37544.16 41186.15 39262.44 1314.91 2.478% numa05.sh Real: 411.57 457.20 433.29 16.58 0.380% numa05.sh Sys: 230.05 435.48 339.95 67.58 -17.9% numa05.sh User: 33325.54 36896.31 35637.84 1222.64 -2.12% Signed-off-by: Srikar Dronamraju --- kernel/sched/fair.c | 20 ++------------------ 1 file changed, 2 insertions(+), 18 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 57d1ee8..ea32a66 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1507,28 +1507,12 @@ static bool load_too_imbalanced(long src_load, long dst_load, src_capacity = env->src_stats.compute_capacity; dst_capacity = env->dst_stats.compute_capacity; - /* We care about the slope of the imbalance, not the direction. */ - if (dst_load < src_load) - swap(dst_load, src_load); - - /* Is the difference below the threshold? */ - imb = dst_load * src_capacity * 100 - - src_load * dst_capacity * env->imbalance_pct; - if (imb <= 0) - return false; + imb = abs(dst_load * src_capacity - src_load * dst_capacity); - /* - * The imbalance is above the allowed threshold. - * Compare it with the old imbalance. - */ orig_src_load = env->src_stats.load; orig_dst_load = env->dst_stats.load; - if (orig_dst_load < orig_src_load) - swap(orig_dst_load, orig_src_load); - - old_imb = orig_dst_load * src_capacity * 100 - - orig_src_load * dst_capacity * env->imbalance_pct; + old_imb = abs(orig_dst_load * src_capacity - orig_src_load * dst_capacity); /* Would this change make things worse? */ return (imb > old_imb); -- 1.8.3.1